Method of producing a package with a corner seal



Oct. 6, 1970 c. A. BJORKENGREN ETAL 3,531,906

METHOD OF PRODUCING A PACKAGE WITH A CORNER SEAL Original Filed Nov. 9, 1966 2 Sheets-Sheet 1 INVENTO'RS- CqrL AXeL Bjorken ren FrqnsWiLheLm Jo an on PM soabggzhx P I Auzorng 1970 c. A. BJORKENGREN ETAL 3,531,906

METHOD OF PRODUCING A PACKAGE WITH A CORNER SEAL Original Filed Nov. 9, 1966 2 Sheets-Sheet 2 INVENTDRS CarL AXeL BJor/(engren Frans \A/dheLrn JOhGhSson wwb . At ornegs 3,531,906 METHOD OF PRODUCING A PACKAGE WITH A CORNER SEAL Carl Axel Bjorkengren, Akarp, and Frans W. Johansson, Sandby, Sweden, assignors to AB Akerlund & Rausing, a Swedish joint-stock company Original application Nov. 9, 1966, Ser. No. 593,066, now Patent No. 3,372,859. Divided and this application Nov. 30, 1967, Ser. No. 687,033 Claims priority, application Sweden, Dec. 9, 1965, 15,941/ 65 Int. Cl. B65b 43/00 US. CI. 53-29 3 Claims ABSTRACT OF THE DISCLOSURE A pillow-shaped package made from a tube of thermoplastic material which is somewhat fiattened when filled and transversely sealed with narrow transverse sealing zones at opposite ends of the package. The four corners of the package at the junction of the transverse sealing zones with the longitudinal edges, and which would normally be subject to fracture due to repeated bending along the line of the transverse sealing zones are strengthened by establishing an additional seal zone at each corner portion and which extends across the corner between the longitudinal edge of the package and the adjacent transverse sealing zone. The pressure utilized for establishing the corner seals of the package is less than that utilized for establishing the transverse seal zones.

The present invention which constitutes a division of our co-pending application, Ser. No. 593,066, filed Nov. 9, 1966 entitled Package With a Corner Seal, now Pat. No. 3,372,859 relates to a package consisting of a material which is heat sealed at least on the side facing the interior of the package and which includes at least one narrow sealing zone which is located parallel to and close to one of the edges of the package and which intersects one or more of the other edges of the package. Preferably, a package of this kind is contemplated which has been made by the forming of a web material into a tube and transversely sealing said tube within narrow transverse zones, which will thus each constitute a sealing zone of the kind defined above.

In packages of the abovementioned kind, e.g. so called cushion or pillow-shaped packages, sealing problems will arise at the points where said sealing zone intersects the package edges. At these points breaking occurs quite easily owing to the fact that repeated bending of the sealing fin situated beyond the sealing zone will take place there.

The present invention solves the abovementioned sealing problem by the feature that the package is provided with one or more additional sealing zones disposed in an angular relation to said sealing zone and arranged so that they preventively seal the packages within the point or points at which said first-mentioned sealing zone intersects said other edges.

Preferably, the additional sealing zones are four in number, which together with the longitudinal edges of the package and the transverse sealing zones define preferably isosceles rectangular triangles. The additional sealing zones are preferably produced by a lighter pressure than the first-mentioned sealing zone which may be produced for example by means of a narrow ruler. This narrow ruler is then pressed against the package with such a pressure that the package will get a folding line, whereby possible bending will take place along this line and not in said additional sealing zones.

The invention will be described more closely in the United States Patent Othce 3,531,906 Patented Oct. 6, 1970 following with reference to the accompanying drawings, which by way of example show a preferred embodiment of the invention and some modifications thereof.

FIGS. 1 and 2 show two mutually rectangular views of a simple pillow-shaped package designed according to the invention.

'FIGS. 3-5 show three alternatives in respect of the design of the corners of the package shown in FIGS. 1 and 2.

In FIGS. 1 and 2 a package'is shown which is made by forming a web material into a tube having a longitudinal seal 1 at which the material is heat sealed with inside against inside. The tube formed has thereupon been given a bottom closure by being heat sealed within a narrow zone 2. In this position the package has been filled via a filling pipe extending down into the tube formed, Whereupon it has been closed at its top by a heat seal in a second narrow sealing zone 3. So far the package according to the invention which consists of two thicknesses of material throughout its area, these forming the front and back walls respectively, does not differ from what is generally known in the art. In such prior bags, however, one has met with difliculties in sealing, because the sealing fins 4 and 5 situated beyond the sealing zones 2 and 3 have been subjected to repeated bending in these sealing zones, whereby leakage has resulted at the points designated by a, where the ends of the sealing zones 2, 3 meet the side, i.e. longitudinal edges of the package. According to the invention the package shown is now provided with one or more additional sealing zones 6 disposed in an angular relation to the sealing zones 2 and 3 and arranged so that they preventively seal the package within the points a. In the example shown these additional sealing zones are four in number, i.e. one at each corner portion of the package which, as seen from the figure, together with the longitudinal edges 7 and 8 of the package and the sealing zones 2 and 3 define isosceles rectangular triangles. Each seal zone is constituted by a plurality of parallel spaced rectilinear seals graduated in length and which extend parallel to a side edge of the package.

Preferably, the sealing zones 6 are produced by a lighter pressure than the sealing zones 3. This may be accomplished for example by mounting the press members for producing the various sealing zones on a single tool but with the press members for the sealing zones 6 arranged farther retracted from the corresponding press members for the sealing zones 2 and 3.

The sealing zones 2 and 3 may be produced by means of a narrow ruler, a pressure such that the finished package will have a folding line in these sealing zones being preferably chosen, whereby a possible bending of the sealing fins 4 and 5 is caused to take place at this line and not in the sealing zones 6.

Preferably, the package material consists of an oxygentight thermoplastic laminate, which has a thickness of the order of one tenth or a few tenths of a millimeter. The sealing zones 2 and 3 may be produced by means of a ruler of a Width of l to 2 millimeters and fixed to a tool, while the sealing zones 6 are produced by press members mounted on the same tool and, as already mentioned, preferably placed slightly farther retracted than the ruler. In practice, it has been found convenient to choose this difference in depth between the various press members of the same order of magnitude as the thickness of material, i.e. half the thickness of the sealing fin.

As an example of material for the package illustrated, a three-ply laminate may be mentioned which may in clude a polyethylene-terephthalate film, a polyester film and a PVDC film having a weight of about grams per square meter and a thickness of about 0.1 millimeter. A great number of other materials may of course also be contemplated, e.g. pure polyethylene. The three-ply laminate described above is primarily intended for packaging coffee or other products sensitive to oxygen.

FIGS. 3, 4 and 5 show alternative designs of the sealing zones 6. Otherwise these figures agree with FIG. 1. In FIG. 3 the sealing zone 6 consists of a broad rectilinear seal 8 disposed at an angle of 45 in relation to the sealing zone 3. In FIG. 4 the sealing zone 6 consists of a narrow diagonally extending rectilinear seal 9 and narrow parallel spaced rectilinear seals 10 disposed at right angles in relation to the sealing zone 3 and which extend from zone 3 to the diagonal seal 9. The seals 10 may be arranged more or less closely spaced and are produced, for example, by means of a grooved press jaw. If the seals are arranged sufficiently closely spaced, the seal 9 may be omitted which is the construction shown in FIG. 1. Alternativelly, the seal 9 may of course be used alone. In FIG. 5 the sealing zone 6 consists of narrow parallel spaced rectilinear seals 11 which are arranged in oblique relation to the sealing zone 3 and which may also be produced by means of a grooved press jaw, these seals 11 being graduated in length and extending between a side edge 7 of the package and transverse seal 3.

Obviously, the invention is not limited to the example described above only but may be varied within the scope of the following claims. Thus, for example, said additional seals may be varied in shape as well as in position.

We claim:

1. The method of producing a pillow-shaped package which comprises the steps of partially flattening a length of tubular thermoplastic material to establish the front and back walls of the package, pressure heat-sealing the front and back walls of said tube along a first transverse seal to form the bottom of the package, filling the package, pressure heat-sealing the front and back walls at the top of the filled package along a second transverse seal and pressure heat-sealing the front and back walls together at each corner portion of the package to form corner seals which extend from a side edge thereof to the adjacent transverse seal thereby to seal off the junction points at the ends of said transverse seals with the side edges of the package, the pressure for forming said corner seals being less than that for forming said tranverse seals.

2. A method as defined in claim 1 wherein the corner seals are formed diagonally across the angles between the transverse seals and the side edges of the package.

3. A method as defined in claim 1 wherein the corner seals are formed by diagonal seals extending across the angles between the transverse seals and the side edges of the package and by at least one seal extending parallel to the side edge from each diagonal seal to the adjacent transverse seal.

References Cited UNITED STATES PATENTS 2,635,788 4/1953 Snyder et a1 229-62 X 2,779,462 1/1957 Hoag. 2,948,999 8/1960 Schlayer et al. 5329 3,380,646 4/1968 Doyen et al. 229-53 X 3,381,886 5/1968 Goglio 229-53 X TRAVIS S. MCGEHEE, Primary Examiner U.S. Cl. X.R. 5339 

